I needed to heat the bottles along the score line to get a proper break. Many people suggested using a candle to heat the bottle, the problem was it left soot along the score and didn't seem to have enough heat. When I was a kid my crazy uncle taught me to carve wax figurines for crating pewter molds. He used a denatured alcohol lamp to heat the tools. It was clean and produced a hot flame.
He made his first few, but bought them in the end, but why buy one when you have all the stuff laying around the house.
Step 1: Materials
A baby food jar (glass with metal lid)
shoe string (cotton)
Awl or punch
Block of wood